Variometer



" Ma 22,1923. I F. P DON LE VARIOMETER 1922 2 Sheets-Sheet Filed Feb- 17 Patented May 2 2, 1923.

PATENT OFFICE.

UNITED STATES HAROLD POTTER DONITE, OF MEEIIDEN, CONNECTICUT, ASSIGNOR TO THE CPN- NECTICUT TELEPHONE 8c ELECTRIC COMPANY, INCORPORATED, OF MERI- DEN,- CONNECTICUT, A CORPORATION'OF CONNECTICUT.

'VARIOMETER.

T all whom it'may concern Be it known that I, HAROLD P. Down, a citizen of the United States of America, residing at Meriden, Connecticut, have 1n- 6 vented a new and useful Variometer, of-

which thefollowing is a specification.

My invention relates particularly to apparatus intended to be used in radio signalling systems.

The main object of my invention is to provide a variable inductive apparatus characterized by' a considerable range and ease of adjustment of inductance values, relatively small and constant electrical re- 15 sistance, and low distributed capacity. Another object is to make such a device compact,'simple, light yet durable, and at a relatively low cost.- 'When used for instance in a radio receiver, my device" ac- 20 commodates a large range of wave lengths, provides 'simple tuning adjustments with small electrical losses. I have shown it in a form .which is easily portable, and although economically made, it is durable.

Fig. 1 is an edge view of one form of device embodying the improvements of my invention; I

Fig. 2 is a front view of the same.

Fig. 3 is a view of the back of the face 30 plate with attached mechanism with the movablecoil' member in the position of maximum total inductance (dial 10).-

. Fig. 4 shows one of the coils in full lines in one position (dial 10). In dot and dash 5 outline it indicates angular adjustment.

" Fig. 5 shows another coil member.

Figs. 4 and-5 the winding is merely suggested. I

Fig. 6 is a transverse sectional view of 40 the principal parts of the apparatus.

Fig. 7 is a rear-view of the dial andoperating knob.

Fig. 8 shows on an enlarged scale a detail of the winding.

In the form shown, which of course it is understood is only one form which my in- .vention may take, the box 10 has a cover 11 held in place-by screws 12. The cover carries circuit terminals 13 and 14 and also to an adjusting knob 15 with an indicating dial 16.

vide a slot with shoulder 17 coacting with At the back of the knob I pro-- a stationary stop pin 18 to limit the rotative movement of the knob and other parts at the interior of the box.

Inside of the box are mounted a plurality of coil members, at least one of which is stationary, and at least one of which is rotatable. In the form shown there are two of these coil members 19 and 20. The coil member 19 is carried by a sleeve 21 which projects rearwardly from the cover or front plate of the'box, and the coil member is carried by the spindle 22 which is secured to the operating knob 15. The sleeve 21 is stationary and the coil member 19 may be secured to it in a suitable manner, for in stance, by means of a metal hub 23 and set screw. Similarly the coil member 20 may be secured to the shaft 22 by a hub 24: and set screw so that the coil members may be readily attached or adjusted on their respective supports. resilient washer 25 in the back of the operating knob to hold the hub 24C in yield ing contact withthe end of the sleeve 21. It will be seen that the two coil members may be adjusted closer together or further apart by simply sliding the hub 23'and its coil member along the sleeve 21, and then securing it in place by the set screw. By make ing the spacing between the two coil members as small as is mechanically feasible,

the ratio of maximum inductance to minimum inductance, or, in other words, the range of the instrument is made extremely large.

The coil-members may be all identical and each may consist of asingle length of wire especially wound so as to provide two oppositely disposed polygonal parts. In this form, each part is spirally wound on a slotted support so that short lengths zig I may also provide a zag back and forth, first on one side and then on'the other side of the support, adjacent turns crossing each other in the slots at intervals. The two parts are so wound and connected that the current travels in them in opposite directions. Preferably, the supporting part of each coil member is formed of a plate of insulating material having a central arm 28 and two extended heads 26 and 27 on opposite ends of the arm. Each of these heads is provided with an uneven number of peripheral slots such as 29 and 3t), through which the conductor 31 is wound zig zag' back and TiiOltll. In the torinshown. the movable coil member 20 has part ot conductor on the h ad 26 wound le'lithandwl,and the otherpart wound righthanded on the head 27. One end of the conductor is electrically connected to the contact member 32. and the other end of the conductor is connected to the hub Qt.

The instrument terminal 14 at its 2' an end carries the arm 3 which is preterahly pivoted and somewhat resilient so as to hold its pin ll in the hole in the contact member 12, and thus maintain electrical contact as the coil member 20 is rotated by the knob 15. This construction also permits the arm 33 to be swung out ot the way to permit the coil member 20-to be removed trom theshatt 22.

The-coil member 19 is constructed simila rly to the coil member 20. Its conductor 35 has one end connected to the hub 23, and the other end connected to the instrument terminal 13.

lVhen the parts are in position with the dial at 10, viz, the position of maximum in duotance, the circuit from terminals l't to 13 is as follows: From 14 to arm 38, contact 32, thence as viewed from the back around the coil head 27 anticlockwise (opposite to direction of the arrows which show the direction of winding) from the outer to the inner edge,'thence across .to the. outer turn of coil head 26 and'clockwise to the center and hub 2 1-. From here thecircuit may be traced to the hub 23 and inner turn of the coil .rire 35 clockwise "(with the direction of winding as indicated by the arrows Fig. 5)

to the outer turn and across to the inner turn of the lower coil part and couliter-clockwise to the'outer turn and the terminal 13.

lly rotating the coil member 20 more or less, 'ariations in the total etl'ective inductance ot the two serially connected coil members are produced. The Zig zag wound coils have practically all of the ad antagcs of ordinary spiral coils of single wire thickness without the dilliculties of construction ordinarily ihhcrent in such devices. At the same time these coil members have a low distributed capacity without material reduction of inductance or increased resistance. AL though the coils are comparatively easy and inexpensive to construct, they are compact and durable, and may be conveniently handled and shipped without danger of breakage.

I cla 1m:

1. A variometcr coil member comprising an insulating plate having a central arm portion with extended slotted heads at opposite ends thereof and a conductor spirally wound in polygonal torin zig-Zag back and forth from one side to the other through said slots in a righthand direction on one head. and in a leilt'hand direction on the other head.

A coil member including a hub and a conductor having right and left hand coils on opposite sides of said hub wound in zigzag torm l'roin one side to the other of a central plane.

3. A coil member comprising a single conductor arranged in the shape of two'elongated polygons on opposite sides of a central axis with alternate portions of the conductor of each polygon laid zig-zag from side to side of a central plane.

-t. A coil member conu n'ising an insulat ing plate having a central cross arm and two extended slotted heads. and comluctors wound zig-zag back and forth through the slots on said heads. In a variomcter, two double-ended coil members, each consisting ot a pair of zigzag windings, one ot said members being adjustable to and from the other member in a direction at right. angles to its winding plane, ach winding'consisting of a conductor having successive portions alternating on opposite sides of a central plane.

(5. A variometer comprising a plurality of coil members at least one of which-is stationary. and at least oneot which is rotatable with respect thereto, each coil member consisting of two oppositely disposed parts each of which is wound spirally in zig-zag form "from side to side of a centralplane.

7. In a variometer, a plurality ot flat; double-ended coil windings, each end of each coil winding being arranged in zig-zag form ing being spirally wound back and torth to opposite sides of a central plane.

8. A 'ariomctei; con'iprising an insulating support, circuit terminals carried thereby, a sleeve carried by said support, a shaft supported by said sleeve, a setting knob carried by said shaft, tlat coil members carried by said sleeve and by said shaft respectively, a connection from one of said coil members to one of said terminals, and a pivoted arm carried by the other terminal forming a detachable connection with another coil member.

9. In a variometer, a stationary sleeve, a flat coil winding carried thereby, a shaft mounted in said sleeve, a tlat coil. winding carried by said shatt adjacent the first mentioned coil winding, an operating knob for said shaft, a centrally disposed contact carried by said second coil winding and a spring HAROLD POTTER DONLE. 

